CN114865974A - Motor variable frequency driving circuit and working method - Google Patents
Motor variable frequency driving circuit and working method Download PDFInfo
- Publication number
- CN114865974A CN114865974A CN202110164336.1A CN202110164336A CN114865974A CN 114865974 A CN114865974 A CN 114865974A CN 202110164336 A CN202110164336 A CN 202110164336A CN 114865974 A CN114865974 A CN 114865974A
- Authority
- CN
- China
- Prior art keywords
- resistor
- electrically connected
- circuit
- operational amplifier
- capacitor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
- H02P21/14—Estimation or adaptation of machine parameters, e.g. flux, current or voltage
- H02P21/18—Estimation of position or speed
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/08—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors
- H02H7/085—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors against excessive load
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
- H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
- H02P27/06—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters
- H02P27/08—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters with pulse width modulation
- H02P27/12—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters with pulse width modulation pulsing by guiding the flux vector, current vector or voltage vector on a circle or a closed curve, e.g. for direct torque control
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Inverter Devices (AREA)
Abstract
The invention relates to a motor variable frequency drive circuit, which comprises a main circuit, a frequency conversion power module, a frequency conversion control circuit and a frequency conversion control circuit, wherein the main circuit comprises a variable frequency power module with a three-phase inverter circuit; the current sampling topological circuit is electrically connected with the three-phase inverter circuit; the current sampling circuit is electrically connected with the current sampling topological circuit; the control chip is respectively and electrically connected with the output end of the current sampling circuit and the variable-frequency power module; the current sampling topological circuit comprises a fourth resistor, a fifth resistor and a sixth resistor, wherein the first end of the fourth resistor is electrically connected with the first phase inverter circuit, the first end of the fifth resistor is electrically connected with the second phase inverter circuit, the first end of the sixth resistor is respectively electrically connected with the second end of the fourth resistor, the second end of the fifth resistor and the third phase inverter circuit, and the second end of the sixth resistor is grounded; the current sampling circuit comprises two comparison circuits, and the output ends of the two comparison circuits are electrically connected with the control chip. The motor has low frequency conversion driving cost and reduces the volume of a circuit board. The invention also relates to a working method of the motor variable frequency driving circuit.
Description
Technical Field
The invention relates to a motor variable frequency drive circuit and a working method thereof.
Background
The FOC variable frequency driving scheme controlled by 180-degree sine wave vectors needs to collect motor current, realize analysis of the motor current and estimation and observation of the position of a motor rotor, and is used for realizing control and regulation of the motor rotating speed.
The existing frequency conversion driving mainstream current sampling topological structure is shown in figure 1, three sampling resistors R04/R05/R06 are respectively connected in series in three bridge arms to realize the sampling of the current of the U/V/W three-phase motor and output the current to an MCU and a comparator so as to realize the functions of rotor position estimation, rotating speed control, overcurrent/short circuit protection and the like of the motor. A four-operational-amplifier construction circuit is required to be provided in the sampling topological structure to collect three paths of U/V/W current to an MCU (microprogrammed control unit) for controlling an SVPWM (space vector pulse width modulation) driving algorithm. This is because the current flowing through R04/R05/R06 has two-way characteristics, and therefore, when the current is 0A, the AD voltage value output by the sampling circuit should be at VDD/2, so that when the current is equal to ± xA, the AD voltage is symmetrically output in the range of 0 to VDD around VDD/2, and the sampling range is ensured. Therefore, when the sampling circuit is constructed, one operational amplifier is required to be constructed into a voltage follower, and the output VDD/2 is used as a reference source to provide reference levels for the other three operational amplifiers. The collected currents of each path pass through a comparator in the overcurrent protection circuit shown in the figure, and the output of the comparator is supplied to an overcurrent protection input pin of the variable frequency power module. Because the current sampling topological structure is used for respectively collecting three-phase currents of U/V/W, the overcurrent protection needs to respectively collect three corresponding voltages of the U/V/W phases and then collect the voltages to the comparator for output, and the circuit is complex.
In summary, in the conventional motor variable frequency driving circuit shown in fig. 1, a four-operational amplifier and a four-comparator are required to be used, so that the number of peripheral circuit components is large, the cost is high, and the occupied PCB volume is large.
Disclosure of Invention
The first technical problem to be solved by the present invention is to provide a variable frequency driving circuit for a motor, which can realize the functions of rotor position estimation, rotational speed control, overcurrent/short circuit protection, etc. on the basis of reducing the number of operational amplifiers, eliminating circuits such as comparators, simplifying the circuit structure, reducing the cost, and reducing the size of the circuit board.
The second technical problem to be solved by the present invention is to provide a method for operating a variable frequency driving circuit of a motor in view of the above prior art.
The technical scheme adopted by the invention for solving the first technical problem is as follows: a motor variable frequency drive circuit comprising:
the main circuit comprises a variable frequency power module with a three-phase inverter circuit, and the three-phase inverter circuit is electrically connected with the motor;
the current sampling topological circuit is electrically connected with the three-phase inverter circuit and is used for providing a current sampling framework of the three-phase inverter circuit;
the current sampling circuit is electrically connected with the current sampling topological circuit and is used for acquiring the output current of the current sampling topological circuit;
the control chip is respectively and electrically connected with the output end of the current sampling circuit and the variable-frequency power module and is used for calculating each phase current;
the method is characterized in that: the current sampling topological circuit comprises a fourth resistor, a fifth resistor and a sixth resistor, wherein the first end of the fourth resistor is electrically connected with the first phase inverter circuit, the first end of the fifth resistor is electrically connected with the second phase inverter circuit, the first end of the sixth resistor is respectively electrically connected with the second end of the fourth resistor, the second end of the fifth resistor and the third phase inverter circuit, and the second end of the sixth resistor is grounded;
the current sampling circuit comprises two paths of comparison circuits, wherein two input ends of the first path of comparison circuit are respectively and electrically connected with a first end of a fourth resistor and a first end of a sixth resistor, two input ends of the second path of comparison circuit are respectively and electrically connected with a first end of a fifth resistor and a first end of the sixth resistor, and output ends of the two comparison circuits are electrically connected with the control chip.
Preferably, the first path of comparison circuit includes a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a second capacitor, a third capacitor, and a first operational amplifier; the first end of the seventh resistor is electrically connected with the weak current power supply, the second end of the seventh resistor is electrically connected with the non-inverting input end of the first operational amplifier, the first end of the eighth resistor is electrically connected with the first end of the fourth resistor, the second end of the eighth resistor is electrically connected with the second end of the seventh resistor, the first end of the ninth resistor is electrically connected with the non-inverting input end of the first operational amplifier, the second end of the ninth resistor is grounded, the first end of the tenth resistor is electrically connected with the output end of the first operational amplifier, the second end of the tenth resistor is electrically connected with the control chip, the first end of the eleventh resistor is electrically connected with the first end of the sixth resistor, the second end of the eleventh resistor is electrically connected with the inverting input end of the first operational amplifier, the first end of the twelfth resistor is electrically connected with the non-inverting input end of the first operational amplifier, and the second end of the twelfth resistor is electrically connected with the output end of the first operational amplifier, two ends of the second capacitor are electrically connected between the second end of the eighth resistor and the second end of the eleventh resistor, the first end of the third capacitor is electrically connected with the second end of the tenth resistor, and the second end of the third capacitor is grounded;
the second path of comparison circuit comprises a thirteenth resistor, a fourteenth resistor, a sixteenth resistor, a seventeenth resistor, an eighteenth resistor, a nineteenth resistor, a fifth capacitor, a sixth capacitor and a second operational amplifier; the first end of a thirteenth resistor is electrically connected with a weak current power supply, the second end of a thirteenth resistor is electrically connected with the non-inverting input end of a second operational amplifier, the first end of a fourteenth resistor is electrically connected with the first end of a fourth resistor, the second end of the fourteenth resistor is electrically connected with the second end of the thirteenth resistor, the first end of a sixteenth resistor is electrically connected with the non-inverting input end of the second operational amplifier, the second end of a sixteenth resistor is grounded, the first end of a seventeenth resistor is electrically connected with the output end of the second operational amplifier, the second end of the seventeenth resistor is electrically connected with a control chip, the first end of an eighteenth resistor is electrically connected with the first end of a sixth resistor, the second end of an eighteenth resistor is electrically connected with the inverting input end of the second operational amplifier, the first end of a nineteenth resistor is electrically connected with the non-inverting input end of the second operational amplifier, the second end of a nineteenth resistor is electrically connected with the output end of the second operational amplifier, two ends of the fifth capacitor are electrically connected between the second end of the fourteenth resistor and the second end of the eighteenth resistor, the first end of the sixth capacitor is electrically connected with the second end of the seventeenth resistor, and the second end of the sixth capacitor is grounded.
More simply, the circuit also comprises an overcurrent protection circuit, wherein the input end of the overcurrent protection circuit is electrically connected with the first end of the sixth resistor;
the variable frequency power module also comprises a drive protection circuit, and the output end of the overcurrent protection circuit is electrically connected with the drive protection circuit.
Preferably, the overcurrent protection circuit includes a fifteenth resistor and a fourth capacitor, a first end of the fifteenth resistor is electrically connected to a first end of the sixth resistor, a second end of the fifteenth resistor is electrically connected to a first end of the fourth capacitor, a second end of the fourth capacitor is grounded, and a first end of the fourth capacitor is further electrically connected to the driving protection circuit.
Preferably, the main circuit further comprises a rectifying circuit electrically connected with the strong power supply, and a filtering circuit electrically connected with the rectifying circuit and the variable frequency power module.
The technical scheme adopted by the invention for solving the second technical problem is as follows: the current of two phase inverter circuits is collected by the aid of the non-inverting input ends of the two comparison circuits, the total current of the three phase inverter circuits is collected by the aid of the inverting input ends of the two comparison circuits, the two comparison circuits are used for operational amplification to output two phase currents which can be identified by the control chip, the control chip calculates a third phase current according to the two phase currents, the position of a motor rotor is estimated through analysis of the three phase currents, and control and adjustment of the rotating speed of the motor are achieved.
Compared with the prior art, the invention has the advantages that: the motor frequency conversion driving circuit is matched with a working method of the motor frequency conversion driving circuit, the number of comparison circuits in the current sampling circuit can be reduced based on the change of the current sampling topological circuit, only two comparison circuits are arranged due to the matching of the current sampling topological circuit and the current sampling circuit, three-phase current data can be obtained, the application of an operational amplifier is reduced due to the matching structure of the current sampling topological circuit and the current sampling circuit, the circuit structure is simpler, the cost of the motor frequency conversion driving circuit is also reduced, the size of a circuit board is reduced, and the motor frequency conversion driving circuit is particularly suitable for being applied in miniaturization under the current large trend of cost reduction.
And the over-current protection circuit can obtain the total three-phase current more easily based on the current sampling topological circuit, so that the over-current protection circuit is simpler, the cost of the motor variable frequency drive circuit is further reduced, and the size of the circuit board is reduced.
Drawings
Fig. 1 is a circuit diagram of a variable frequency driving circuit of a motor in the prior art.
Fig. 2 is a circuit diagram of a variable frequency driving circuit of a motor according to an embodiment of the present invention.
Detailed Description
The invention is described in further detail below with reference to the accompanying examples.
As shown in fig. 2, the motor variable frequency driving circuit in this embodiment includes a motor variable frequency driving circuit, which includes a main circuit 1, a current sampling topology circuit 2, a current sampling circuit 3, a control chip MCU, and an overcurrent protection circuit 4.
The main circuit 1 comprises a rectification circuit 12 electrically connected with a strong current power supply, a filter circuit 13 electrically connected with the rectification circuit 12, and a variable frequency power module 11 electrically connected with the filter circuit 13, wherein the variable frequency power module 11 is provided with a three-phase inverter circuit and a drive protection circuit 111, the drive protection circuit 111 and the three-phase inverter circuit can perform overcurrent protection on the three-phase inverter circuit, the three-phase inverter circuit is electrically connected with a motor (M), the three-phase inverter circuit is used for driving the motor (M) to work, and the three phases are defined as a U phase, a V phase and a W phase according to common description habits in the field.
The current sampling topological circuit 2 is electrically connected with the three-phase inverter circuit and is used for providing a current sampling framework of the three-phase inverter circuit. The current sampling topology circuit 2 in this embodiment includes a fourth resistor R4, a fifth resistor R5, and a sixth resistor R6, a first end of the fourth resistor R4 is electrically connected to the first phase inverter circuit, a first end of the fifth resistor R5 is electrically connected to the second phase inverter circuit, a first end of the sixth resistor R6 is electrically connected to a second end of the fourth resistor R4, a second end of the fifth resistor R5, and the third phase inverter circuit, respectively, and a second end of the sixth resistor R6 is grounded. The fourth resistor R4 and the fifth resistor R5 are respectively connected in series in a bridge arm of the two-phase inverter circuit for U, V two-phase current, and the U, V two-phase current and the W-phase current passing through the fourth resistor R4 and the fifth resistor R5 are directly combined and connected to the sixth resistor R6 and then grounded. The currents flowing through the fourth resistor R4 and the fifth resistor R5 are U, V phase currents, respectively, and the current flowing through the sixth resistor R6 is U, V, W total three-phase current.
The current sampling circuit 3 is electrically connected with the current sampling topology circuit 2 and is used for obtaining the current output by the current sampling topology circuit 2. The current sampling circuit 3 only collects U/V two-phase current, and W phase current is obtained through software calculation in the control chip MCU. Therefore, the current sampling circuit 3 in this embodiment only needs two comparing circuits, where two input terminals of the first comparing circuit are electrically connected to the first end of the fourth resistor R4 and the first end of the sixth resistor R6, two input terminals of the second comparing circuit are electrically connected to the first end of the fifth resistor R5 and the first end of the sixth resistor R6, and output terminals of the two comparing circuits are electrically connected to the control chip MCU.
The control chip MCU is respectively and electrically connected with the output end of the current sampling circuit 3 and the variable frequency power module 11, and can calculate each phase current; the currents of the two phases can be directly obtained U, V by the two comparison circuits, and the control chip MCU calculates the current value of the current of the phase W according to the currents of the two phases after obtaining the current information transmitted by the comparison circuits.
In this embodiment, the first path of comparison circuit includes a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a second capacitor C2, a third capacitor C3, and a first operational amplifier IC 301A; a first end of the seventh resistor R7 is electrically connected to the weak current power supply, a second end of the seventh resistor R7 is electrically connected to the non-inverting input terminal of the first operational amplifier IC301A, a first end of the eighth resistor R8 is electrically connected to a first end of the fourth resistor R4, a second end of the eighth resistor R8 is electrically connected to a second end of the seventh resistor R7, a first end of the ninth resistor R9 is electrically connected to the non-inverting input terminal of the first operational amplifier IC301A, a second end of the ninth resistor R9 is grounded, a first end of the tenth resistor R10 is electrically connected to the output terminal of the first operational amplifier IC301A, a second end of the tenth resistor R10 is electrically connected to the MCU, a first end of the eleventh resistor R11 is electrically connected to a first end of the sixth resistor R6, a second end of the eleventh resistor R11 is electrically connected to the inverting input terminal of the first operational amplifier IC301A, a first end of the twelfth resistor R12 is electrically connected to the non-inverting input terminal of the first operational amplifier IC301A, a second end of the twelfth resistor R12 is electrically connected to the output end of the first operational amplifier IC301A, two ends of the second capacitor C2 are electrically connected between the second end of the eighth resistor R8 and the second end of the eleventh resistor R11, a first end of the third capacitor C3 is electrically connected to the second end of the tenth resistor R10, and a second end of the third capacitor C3 is grounded.
The second path of comparison circuit comprises a thirteenth resistor R13, a fourteenth resistor R14, a sixteenth resistor R16, a seventeenth resistor R17, an eighteenth resistor R18, a nineteenth resistor R19, a fifth capacitor C5, a sixth capacitor C6 and a second operational amplifier IC 301B; a first end of a thirteenth resistor R13 is electrically connected to the weak current power supply, a second end of a thirteenth resistor R13 is electrically connected to the non-inverting input terminal of the second operational amplifier IC301B, a first end of a fourteenth resistor R14 is electrically connected to a first end of a fourth resistor R4, a second end of a fourteenth resistor R14 is electrically connected to a second end of the thirteenth resistor R13, a first end of a sixteenth resistor R16 is electrically connected to the non-inverting input terminal of the second operational amplifier IC301B, a second end of a sixteenth resistor R16 is grounded, a first end of a seventeenth resistor R17 is electrically connected to the output terminal of the second operational amplifier IC301B, a second end of a seventeenth resistor R17 is electrically connected to the control chip MCU, a first end of an eighteenth resistor R18 is electrically connected to a first end of a sixth resistor R6, a second end of an eighteenth resistor R18 is electrically connected to the inverting input terminal of the second operational amplifier IC301B, a first end of a nineteenth resistor R19 is electrically connected to the non-inverting input terminal of the second operational amplifier IC301B, a second end of the nineteenth resistor R19 is electrically connected to the output end of the second operational amplifier IC301B, two ends of the fifth capacitor C5 are electrically connected between the second end of the fourteenth resistor R14 and the second end of the eighteenth resistor R18, a first end of the sixth capacitor C6 is electrically connected to the second end of the seventeenth resistor R17, and a second end of the sixth capacitor C6 is grounded.
In the embodiment, the weak current power supply with the voltage of VDD is used as the reference source, and meanwhile, a ninth resistor R9 and a sixteenth resistor R16 are arranged for the comparison circuit to obtain the output of VDD/2 when the phase current is 0A. Specifically, the impedances of the non-inverting input terminal and the inverting input terminal of the first operational amplifier IC301A and the second operational amplifier IC301B need to be matched to be equal to each other, the ninth resistor R9 and the sixteenth resistor R16 can balance the impedances of the non-inverting input terminal and the inverting input terminal of the first operational amplifier IC301A and the second operational amplifier IC301B, so that the parallel impedance of the seventh resistor R7, the eighth resistor R8 and the ninth resistor R9 is equal to the parallel impedance of the eleventh resistor R11 and the twelfth resistor R12, and the parallel impedance of the thirteenth resistor R13, the fourteenth resistor R14 and the sixteenth resistor R16 is equal to the parallel impedance of the eighteenth resistor R18 and the nineteenth resistor R19.
The working method of the motor variable frequency driving circuit comprises the following steps: the current of two phase inverter circuits is collected by the aid of the non-inverting input ends of the two comparison circuits, the total current of the three phase inverter circuits is collected by the aid of the inverting input ends of the two comparison circuits, the two comparison circuits are used for operational amplification to output two phase currents which can be identified by the control chip, the control chip calculates a third phase current according to the two phase currents, the position of a motor rotor is estimated through analysis of the three phase currents, and control and adjustment of the rotating speed of the motor are achieved.
Specifically, the currents collected by the non-inverting input terminals of the first operational amplifier IC301A and the second operational amplifier IC301B are currents flowing through the fourth resistor R4 and the fifth resistor R5, which are currents of a single-phase inverter circuit, the currents collected by the inverting input terminals of the first operational amplifier IC301A and the second operational amplifier IC301B are total currents of the three-phase inverter circuit, and since the total currents of the three-phase inverter circuit are changed currents, in order to ensure a linear relationship between the output voltage and the non-inverting input terminal sampling current, in the calculation process, an influence of a change of the total sampling current at the inverting input terminal needs to be eliminated, and complexity of calculation is reduced, so that it is necessary to ensure that impedances of the non-inverting input terminals and the inverting input terminals of the first operational amplifier IC301A and the second operational amplifier IC301B are equal.
This can be calculated from the characteristics of the virtual short/virtual break of the operational amplifier itself:
the output voltage AD _ IU of the first operational amplifier IC301A is IU R4R 12/R11+ VDD/2, and the U-phase current is calculated according to the calculation formula;
the output voltage AD _ Iv _ R5R 19/R18+ VDD/2 of the second operational amplifier IC301B, and the V-phase current is calculated according to the calculation formula;
the W-phase current is obtained by a control chip MCU in a software calculation mode: since the sum of the current vectors of the three-phase inverter circuit is zero
And (4) calculating and obtaining the current of the W phase without the corresponding comparison circuit. Therefore, the three-phase working current of the motor M is obtained, and the control and regulation of the rotating speed of the motor M are realized by analyzing the motor current and estimating and observing the position of a motor rotor.
The input end of the overcurrent protection circuit 4 is electrically connected with the first end of the sixth resistor R6, the variable frequency power module 11 further includes a driving protection circuit 111, and the output end of the overcurrent protection circuit 4 is electrically connected with the driving protection circuit 111. The over-current protection circuit 4 in this embodiment includes a fifteenth resistor R15 and a fourth capacitor C4, a first end of the fifteenth resistor R15 is electrically connected to a first end of the sixth resistor R6, a second end of the fifteenth resistor R15 is electrically connected to a first end of the fourth capacitor C4, a second end of the fourth capacitor C4 is grounded, and a first end of the fourth capacitor C4 is further electrically connected to the driving protection circuit 111.
In the current sampling topology circuit 2 in this embodiment, U, V two-phase currents correspondingly flow through the fourth resistor R4 and the fifth resistor R5, and then are summed together with the W-phase current to the sixth resistor R6, that is, the instantaneous current flowing through the sixth resistor R6 is a three-phase total current I _ shunt, the total current I _ shunt is connected to the ITRIP pin of the driving protection circuit 111 in the frequency conversion power module 11 through a low-pass filter formed by a fifteenth resistor R15 and a fourth capacitor C4, when the instantaneous current of one or two of the U, V, W three phases exceeds a set overcurrent point, that is, when I _ shunt R6>0.5V, the driving protection circuit 111 in the frequency conversion power module 11 can detect an overcurrent condition, and further turn off the three power tubes Q4, Q5, and Q6 of the lower bridge arm in the three-phase inverter circuit. The time constant of R15/C4 is set to be 1-2 us, and the adjustment of the overcurrent point is realized by adjusting the resistance value of R6; if a short circuit occurs, I _ shunt × R6 must exceed 0.5V, and short circuit protection can be achieved as well, in this way, the comparator and its complex peripheral matching circuit can be saved.
In summary, the motor variable frequency driving circuit can reduce the number of comparison circuits in the current sampling circuit 3 based on the change of the current sampling topology circuit 2, the matching of the current sampling topology circuit 2 and the current sampling circuit 3 enables only two comparison circuits to be arranged, namely three-phase current data can be obtained, the matching structure of the current sampling topology circuit 2 and the current sampling circuit 3 reduces the application of an operational amplifier, the circuit structure is simpler, the cost of the motor variable frequency driving circuit is also reduced, the volume of a circuit board is reduced, and the motor variable frequency driving circuit is particularly suitable for miniaturized application under the current large trend of cost reduction.
And the over-current protection circuit 4 can obtain the total three-phase current more easily based on the current sampling topological circuit 2, so that the over-current protection circuit 4 is simpler, the cost of the motor variable frequency drive circuit is further reduced, and the size of a circuit board is reduced.
Claims (6)
1. A motor variable frequency drive circuit comprising:
a main circuit (1) comprising a variable frequency power module (11) with a three-phase inverter circuit, said three-phase inverter circuit being electrically connected to a motor (M);
the current sampling topological circuit (2) is electrically connected with the three-phase inverter circuit and is used for providing a current sampling framework of the three-phase inverter circuit;
the current sampling circuit (3) is electrically connected with the current sampling topological circuit (2) and is used for acquiring the output current of the current sampling topological circuit (2);
the control chip (MCU) is respectively and electrically connected with the output end of the current sampling circuit (3) and the variable-frequency power module (11);
the method is characterized in that: the current sampling topology circuit (2) comprises a fourth resistor (R4), a fifth resistor (R5) and a sixth resistor (R6), wherein the first end of the fourth resistor (R4) is electrically connected with the first phase inverter circuit, the first end of the fifth resistor (R5) is electrically connected with the second phase inverter circuit, the first end of the sixth resistor (R6) is respectively electrically connected with the second end of the fourth resistor (R4), the second end of the fifth resistor (R5) and the third phase inverter circuit, and the second end of the sixth resistor (R6) is grounded;
the current sampling circuit (3) comprises two paths of comparison circuits, wherein two input ends of the first path of comparison circuit are respectively electrically connected with a first end of a fourth resistor (R4) and a first end of a sixth resistor (R6), two input ends of the second path of comparison circuit are respectively electrically connected with a first end of a fifth resistor (R5) and a first end of a sixth resistor (R6), and output ends of the two comparison circuits are electrically connected with a control chip (MCU).
2. The variable frequency drive circuit of the motor of claim 1, wherein: the first path of comparison circuit comprises a seventh resistor (R7), an eighth resistor (R8), a ninth resistor (R9), a tenth resistor (R10), an eleventh resistor (R11), a twelfth resistor (R12), a second capacitor (C2), a third capacitor (C3) and a first operational amplifier (IC 301A); a first end of a seventh resistor (R7) is electrically connected with a weak current power supply, a second end of a seventh resistor (R7) is electrically connected with a non-inverting input end of a first operational amplifier (IC301A), a first end of an eighth resistor (R8) is electrically connected with a first end of a fourth resistor (R4), a second end of an eighth resistor (R8) is electrically connected with a second end of a seventh resistor (R7), a first end of a ninth resistor (R9) is electrically connected with a non-inverting input end of the first operational amplifier (IC301A), a second end of a ninth resistor (R9) is grounded, a first end of a tenth resistor (R10) is electrically connected with an output end of the first operational amplifier (IC301A), a second end of a tenth resistor (R10) is electrically connected with a control chip (MCU), a first end of an eleventh resistor (R11) is electrically connected with a first end of a sixth resistor (R6), a second end of an eleventh resistor (R11) is electrically connected with an inverting input end of the first operational amplifier (IC301A), a first end of a twelfth resistor (R12) is electrically connected with a non-inverting input end of the first operational amplifier (IC301A), a second end of the twelfth resistor (R12) is electrically connected with an output end of the first operational amplifier (IC301A), two ends of a second capacitor (C2) are electrically connected between a second end of the eighth resistor (R8) and a second end of the eleventh resistor (R11), a first end of a third capacitor (C3) is electrically connected with a second end of the tenth resistor (R10), and a second end of the third capacitor (C3) is grounded;
the second path of comparison circuit comprises a thirteenth resistor (R13), a fourteenth resistor (R14), a sixteenth resistor (R16), a seventeenth resistor (R17), an eighteenth resistor (R18), a nineteenth resistor (R19), a fifth capacitor (C5), a sixth capacitor (C6) and a second operational amplifier (IC 301B); a first end of a thirteenth resistor (R13) is electrically connected with a weak current power supply, a second end of a thirteenth resistor (R13) is electrically connected with a non-inverting input end of a second operational amplifier (IC301B), a first end of a fourteenth resistor (R14) is electrically connected with a first end of a fourth resistor (R4), a second end of a fourteenth resistor (R14) is electrically connected with a second end of a thirteenth resistor (R13), a first end of a sixteenth resistor (R16) is electrically connected with a non-inverting input end of a second operational amplifier (IC301B), a second end of a sixteenth resistor (R16) is grounded, a first end of a seventeenth resistor (R17) is electrically connected with an output end of the second operational amplifier (IC301B), a second end of a seventeenth resistor (R17) is electrically connected with a control chip (MCU), a first end of an eighteenth resistor (R18) is electrically connected with a first end of a sixth resistor (R6), a second end of an eighteenth resistor (R18) is electrically connected with an inverting input end of a second operational amplifier (IC301B), a first end of a nineteenth resistor (R19) is electrically connected with a non-inverting input end of the second operational amplifier (IC301B), a second end of the nineteenth resistor (R19) is electrically connected with an output end of the second operational amplifier (IC301B), two ends of a fifth capacitor (C5) are electrically connected between a second end of the fourteenth resistor (R14) and a second end of the eighteenth resistor (R18), a first end of a sixth capacitor (C6) is electrically connected with a second end of the seventeenth resistor (R17), and a second end of the sixth capacitor (C6) is grounded.
3. The motor variable frequency drive circuit according to claim 1 or 2, characterized in that: the overcurrent protection circuit (4) is further included, and the input end of the overcurrent protection circuit (4) is electrically connected with the first end of the sixth resistor (R6);
the variable-frequency power module (11) further comprises a drive protection circuit (111), and the output end of the overcurrent protection circuit (4) is electrically connected with the drive protection circuit (111).
4. The motor variable frequency drive circuit of claim 3, wherein: the overcurrent protection circuit (4) comprises a fifteenth resistor (R15) and a fourth capacitor (C4), wherein a first end of the fifteenth resistor (R15) is electrically connected with a first end of a sixth resistor (R6), a second end of the fifteenth resistor (R15) is electrically connected with a first end of the fourth capacitor (C4), a second end of the fourth capacitor (C4) is grounded, and a first end of the fourth capacitor (C4) is electrically connected with the drive protection circuit (111).
5. The motor variable frequency drive circuit according to claim 1 or 2, characterized in that: the main circuit (1) further comprises a rectifying circuit (12) electrically connected with the strong power supply, and a filter circuit (13) electrically connected with the rectifying circuit (12) and the variable-frequency power module (11).
6. A method for operating a variable frequency drive circuit of an electric motor according to any one of claims 1 to 5, characterized by: the current of two phase inverter circuits is collected by the aid of the non-inverting input ends of the two comparison circuits, the total current of the three phase inverter circuits is collected by the aid of the inverting input ends of the two comparison circuits, the two comparison circuits are used for operational amplification to output two phase currents which can be identified by the control chip, the control chip calculates a third phase current according to the two phase currents, the position of a motor rotor is estimated through analysis of the three phase currents, and control and adjustment of the rotating speed of the motor are achieved.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110164336.1A CN114865974A (en) | 2021-02-05 | 2021-02-05 | Motor variable frequency driving circuit and working method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110164336.1A CN114865974A (en) | 2021-02-05 | 2021-02-05 | Motor variable frequency driving circuit and working method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN114865974A true CN114865974A (en) | 2022-08-05 |
Family
ID=82627130
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110164336.1A Pending CN114865974A (en) | 2021-02-05 | 2021-02-05 | Motor variable frequency driving circuit and working method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114865974A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116169633A (en) * | 2023-04-25 | 2023-05-26 | 广东汇芯半导体有限公司 | Current protection semiconductor circuit |
-
2021
- 2021-02-05 CN CN202110164336.1A patent/CN114865974A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116169633A (en) * | 2023-04-25 | 2023-05-26 | 广东汇芯半导体有限公司 | Current protection semiconductor circuit |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN100472935C (en) | Controlling device and its regulating method of synchronous motor | |
| Rodriguez et al. | A novel direct torque control scheme for induction machines with space vector modulation | |
| CN107222135B (en) | A kind of D-C brushless electric machine no-position sensor control system phase change control method | |
| CN107834919B (en) | current response type permanent magnet synchronous motor and single-phase simulator of driving system thereof | |
| JP2004215406A (en) | Motor driver for air conditioner | |
| CN114865974A (en) | Motor variable frequency driving circuit and working method | |
| CN214799345U (en) | Motor frequency conversion drive circuit | |
| US20240014758A1 (en) | Power conversion device | |
| CN214480360U (en) | Universal application circuit for three-phase, two-phase and single-phase resistance sampling | |
| Gonzalez-Gutierrez et al. | A PC-based architecture for parameter analysis of vector-controlled induction motor drive | |
| CN109981017B (en) | Fault-tolerant control system and method for two-unit same-phase permanent magnet synchronous motor under open-circuit fault | |
| CN107947684A (en) | A kind of DC bus-bar voltage guard method and device | |
| CN207380494U (en) | A kind of three-phase variable frequency motor difference sample circuit | |
| CN106712602B (en) | Control device and control method based on position-sensor-free permanent magnet synchronous motor | |
| CN107589293A (en) | A kind of current sampling circuit | |
| CN113872485A (en) | Motor control method, device, equipment, system and storage medium | |
| CN107565873A (en) | The terminal voltage measurement apparatus and measuring method of motor | |
| CN207198222U (en) | A kind of current sampling circuit | |
| CN211296611U (en) | Neural network current controller and device | |
| WO2022006847A1 (en) | Three-phase three-wire system current sampling circuit and method | |
| CN212808420U (en) | Three-phase three-wire system current sampling circuit | |
| CN112910363B (en) | Square wave and sine wave integrated control system for magnetic suspension permanent magnet motor | |
| CN111220837A (en) | Output voltage detector of broadband PWM frequency converter | |
| CN112398382B (en) | Method and device for detecting phase current | |
| CN113659844B (en) | Harmonic control device and method for frequency converter and frequency converter |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |